Exosomal PGAM1 promotes prostate cancer angiogenesis and metastasis by interacting with ACTG1.

Tumor-derived exosomes and their contents promote cancer metastasis. Phosphoglycerate mutase 1 (PGAM1) is involved in various cancer-related processes. Nevertheless, the underlying mechanism of exosomal PGAM1 in prostate cancer (PCa) metastasis remains unclear. In this study, we performed in vitro and in vivo to determine the functions of exosomal PGAM1 in the angiogenesis of patients with metastatic PCa. We performed Glutathione-S-transferase pulldown, co-immunoprecipitation, western blotting and gelatin degradation assays to determine the pathway mediating the effect of exosomal PGAM1 in PCa. Our results revealed a significant increase in exosomal PGAM1 levels in the plasma of patients with metastatic PCa compared to patients with non-metastatic PCa. Furthermore, PGAM1 was a key factor initiating PCa cell metastasis by promoting invadopodia formation and could be conveyed by exosomes from PCa cells to human umbilical vein endothelial cells (HUVECs). In addition, exosomal PGAM1 could bind to γ-actin (ACTG1), which promotes podosome formation and neovascular sprouting in HUVECs. In vivo results revealed exosomal PGAM1 enhanced lung metastasis in nude mice injected with PCa cells via the tail vein. In summary, exosomal PGAM1 promotes angiogenesis and could be used as a liquid biopsy marker for PCa metastasis.

LncRNA SNHG1 and RNA binding protein hnRNPL form a complex and coregulate CDH1 to boost the growth and metastasis of prostate cancer.

The interaction between LncRNA and RNA-binding protein (RBPs) plays an essential role in the regulation over the malignant progression of tumors. Previous studies on the mechanism of SNHG1, an emerging lncRNA, have primarily focused on the competing endogenous RNA (ceRNA) mechanism. Nevertheless, the underlying mechanism between SNHG1 and RBPs in tumors remains to be explored, especially in prostate cancer (PCa). SNHG1 expression profiles in PCa were determined through the analysis of TCGA data and tissue microarray at the RNA level. Gain- and loss-of-function experiments were performed to investigate the biological role of SNHG1 in PCa initiation and progression. RNA-seq, immunoblotting, RNA pull-down and RNA immunoprecipitation analyses were utilized to clarify potential pathways with which SNHG1 might be involved. Finally, rescue experiments were carried out to further confirm this mechanism. We found that SNHG1 was dominantly expressed in the nuclei of PCa cells and significantly upregulated in PCa patients. The higher expression level of SNHG1 was dramatically correlated with tumor metastasis and patient survival. Functionally, overexpression of SNHG1 in PCa cells induced epithelial-mesenchymal transition (EMT), accompanied by down-regulation of the epithelial marker, E-cadherin, and up-regulation of the mesenchymal marker, vimentin. Increased proliferation and migration, as well as accelerated xenograft tumor growth, were observed in SNHG1-overexpressing PCa cells, while opposite effects were achieved in SNHG1-silenced cells. Mechanistically, SNHG1 competitively interacted with hnRNPL to impair the translation of protein E-cadherin, thus activating the effect of SNHG1 on the EMT pathway, eventually promoting the metastasis of PCa. Our findings demonstrate that SNHG1 is a positive regulator of EMT activation through the SNHG1-hnRNPL-CDH1 axis. SNHG1 may serve as a novel potential therapeutic target for PCa.

Phosphoribosyl pyrophosphate synthetases 2 knockdown inhibits prostate cancer progression by suppressing cell cycle and inducing cell apoptosis.

Phosphoribosyl pyrophosphate synthetases 2 (PRPS2) protein function as nucleotide synthesis enzyme that plays vital roles in cancer biology. However, the expression profile and function of PRPS2 in prostate cancer (PCa) remain to be identified. Here we investigated the expression of PRPS2 protein in human PCa and paired normal tissues by immunohistochemistry, meanwhile the regulatory effects on cell proliferation, apoptosis and growth of xenograft tumors in nude mice were evaluated in PCa cells with PRPS2 depletion. Moreover, the signaling pathways were also explored by western blot analysis and quantitative polymerase chain reaction assays. We found that PRPS2 was dramatically upregulated in prostate adenocarcinoma tissues in comparison with normal tissues, and that increased PRPS2 was linked intimately to advanced clinical stage and pT status. Functional experiments showed that knockdown of PRPS2 significantly suppressed cell growth both in vitro and in vivo. In addition, depletion of PRPS2 induced G1 phase cell cycle arrest and elevated cell apoptosis. Silencing of PRPS2 resulted in the decreased expression of Bcl­2 and cyclinD1 and increased levels of Bax, cleavage of caspases­3, caspases­9 and PARP. Furthermore, we also detected PRPS2 expression was significantly induced after DHT treatment, which implied the important role of PRPS2 in oncogenesis of PCa. Taken together, our findings elucidated that PRPS2 may be a potential novel candidate for PCa therapy.

Phosphoribosyl-pyrophosphate synthetase 2 (PRPS2) depletion regulates spermatogenic cell apoptosis and is correlated with hypospermatogenesis.

Phosphoribosyl-pyrophosphate synthetase 2 (PRPS2) is a rate-limiting enzyme and plays an important role in purine and pyrimidine nucleotide synthesis. Recent studies report that PRPS2 is involved in male infertility. However, the role of PRPS2 in hypospermatogenesis is unknown. In this study, the relationship of PRPS2 with hypospermatogenesis and spermatogenic cell apoptosis was investigated. The results showed that PRPS2 depletion increased the number of apoptotic spermatogenic cells in vitro. PRPS2 was downregulated in a mouse model of hypospermatogenesis. When PRPS2 expression was knocked down in mouse testes, hypospermatogenesis and accelerated apoptosis of spermatogenic cells were noted. E2F transcription factor 1 (E2F1) was confirmed as the target gene of PRPS2 and played a key role in cell apoptosis by regulating the P53/Bcl-xl/Bcl-2/Caspase 6/Caspase 9 apoptosis pathway. Therefore, these data indicate that PRPS2 depletion contributes to the apoptosis of spermatogenic cells and is associated with hypospermatogenesis, which may be helpful for the diagnosis of male infertility.

HMGB1 Promotes Prostate Cancer Development and Metastasis by Interacting with Brahma-Related Gene 1 and Activating the Akt Signaling Pathway.

Background and Aim: We have previously shown that high-mobility group box 1 (HMGB1) is an independent biomarker for shortened survival of prostate cancer (PCa) patients. However, the specific role of HMGB1 in tumor development and progression remains largely unknown. In this study, we investigated the molecular mechanisms of HMGB1 in PCa tumorigenesis. Methods: Gain-of-function and loss-of-function experiments were used to determine the biological functions of HMGB1 both in vitro and in vivo. Bioinformatic analysis, immunoprecipitation, and immunofluorescence assays were applied to discern and examine the relationship between HMGB1 and its potential targets. Specimens from 64 patients with PCa were analyzed for the expression of HMGB1 and its relationship with Brahma-related gene 1 (BRG1) was examined by immunohistochemistry. Results: The results demonstrated that ectopic expression of HMGB1 facilitated growth and metastasis of PCa by enhancing Akt signaling pathway and promoting epithelial-mesenchymal transition (EMT), while silencing of HMGB1 showed the opposite effects. Mechanistically, HMGB1 exerted these functions through its interaction with BRG1 which may augment BRG1 function and activate the Akt signaling pathway thereby promoting EMT. Importantly, both HMGB1 and BRG1 expression was markedly increased in human PCa tissues. Conclusions: Taken together, these findings indicate that upregulation of HMGB1 promotes PCa development via activation of Akt and accelerates metastasis through regulating BRG1-mediated EMT. HMGB1 could be used as a novel potential target for the treatment of PCa.

Suppressed epithelial-mesenchymal transition and cancer stem cell properties mediate the anti-cancer effects of ethyl pyruvate via regulation of the AKT/nuclear factor-κB pathway in prostate cancer cells.

Castration-resistant prostate cancer (CRPC) is a leading cause of mortality among cases of prostate cancer (PCa). Current treatment options for CRPC are limited. Ethyl pyruvate (EP), a lipophilic derivative of pyruvic acid, has been reported to have antitumor activities. In the present study, the efficacy of EP against PCa was investigated using two human PCa cell lines and a mouse xenograft tumor model. PC3 and CWR22RV1 cells were treated with EP, and cytotoxicity was evaluated via Cell Counting Kit-8 and colony formation assays, while cell cycle distribution was assessed by flow cytometry. Changes in cell migration and invasion caused by EP treatment were also evaluated with Transwell and wound healing assays, and changes in the expression of intracellular signaling pathway components were detected by western blotting. EP treatment reduced cell viability, induced G1 arrest, and activated the intrinsic apoptosis pathway. Additionally, the in vivo experiments revealed that EP administration markedly inhibited tumor growth. EP also reversed epithelial-mesenchymal transition and suppressed cancer stem cell properties in part through negative regulation of AKT/nuclear factor-κB signaling. These results indicate that EP has anticancer activity in vitro and in vivo, and is therefore a promising therapeutic agent for the treatment of PCa.

Phosphoglycerate mutase 1 knockdown inhibits prostate cancer cell growth, migration, and invasion.

Phosphoglycerate mutase 1 (PGAM1) is upregulated in many cancer types and involved in cell proliferation, migration, invasion, and apoptosis. However, the relationship between PGAM1 and prostate cancer is poorly understood. The present study investigated the changes in PGAM1 expression in prostate cancer tissues compared with normal prostate tissues and examined the cellular function of PGAM1 and its relationship with clinicopathological variables. Immunohistochemistry and Western blotting revealed that PGAM1 expression was upregulated in prostate cancer tissues and cell lines. PGAM1 expression was associated with Gleason score (P = 0.01) and T-stage (P = 0.009). Knockdown of PGAM1 by siRNA in PC-3 and 22Rv1 prostate cancer cell lines inhibited cell proliferation, migration, and invasion and enhanced cancer cell apoptosis. In a nude mouse xenograft model, PGAM1 knockdown markedly suppressed tumor growth. Deletion of PGAM1 resulted in decreased expression of Bcl-2, enhanced expression of Bax, caspases-3 and inhibition of MMP-2 and MMP-9 expression. Our results indicate that PGAM1 may play an important role in prostate cancer progression and aggressiveness, and that it might be a valuable marker of poor prognosis and a potential therapeutic target for prostate cancer.